Zinc oxide diodes for optical interconnections

ABSTRACT

The present disclosure includes methods, devices, and systems for zinc oxide diodes for optical interconnections. One system includes a ZnO emitter confined within a circular geometry in an oxide layer on a silicon substrate. An optical waveguide is formed in the oxide layer and has an input coupled to the ZnO emitter. A detector is coupled to an output of the optical waveguide.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor devices and,more particularly, to zinc oxide diodes for optical interconnections.

BACKGROUND

A continuing challenge in the semiconductor industry is to find new,innovative, and efficient ways of forming electrical connections withand between circuit devices which are fabricated on the same and ondifferent wafers or dies. In addition, continuing challenges are posedto find and/or improve upon the packaging techniques utilized to packageintegrated circuitry devices.

One technique to alleviate these problems is optical interconnectionsbetween integrated circuits on the same die, adjacent die, or integratedcircuits on a board. These interconnections can either be through air,optical waveguides or optical fibers. Since many integrated circuitsinclude circuits formed from silicon based semiconductors, it would bedesirable to use detectors also formed from silicon, e.g., a siliconphotodiode or a metal-semiconductor-metal detector on silicon, etc. Suchsilicon based detectors have can only detect short wavelengths in theultraviolet where silicon is strongly absorbing. Unfortunately,producing signals having such short wavelengths and accomplishingsignaling implementations through appropriate waveguides to thedetectors is more difficult to achieve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a cross sectional view of an embodiment of a ZnOlight emitting diode (LED) for use in optical interconnects withsemiconductor integrated circuits (ICs).

FIG. 1B illustrates an embodiment of a ZnO diode with a conductivecontact to the ZnO diode such that the conductive contact defines acircular opening.

FIG. 2 illustrates an embodiment of a ZnO diode optically interconnectedthrough an airgap to a silicon detector.

FIG. 3 illustrates an embodiment of a ZnO diode optically interconnectedthrough a waveguide to a silicon detector.

FIG. 4A illustrates an optical fiber waveguide with an inner core andouter cladding according to an embodiment of the present disclosure.

FIG. 4B illustrates a cross-sectional view of an optical fiber waveguidewith an inner core and outer cladding according to an embodiment of thepresent disclosure.

FIG. 5 illustrates a cross-sectional view of an optical fiber waveguidewith an inner core, an outer cladding, and an opening through thecenter, according to an embodiment of the present disclosure.

FIG. 6 illustrates the index of refraction across the cross section ofthe optical fiber waveguide of the embodiment shown in FIG. 4B.

FIG. 7 illustrates the index of refraction across the cross section ofthe optical fiber waveguide of the embodiment shown in FIG. 5.

FIG. 8 illustrates an optical system including an emitter that sends asignal through a waveguide to a receiver according to embodiments of thepresent disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure include systems, methods, anddevices for optical signaling. Embodiments include a Zinc Oxide (ZnO)emitter and a silicon detector in an optical interconnection. One methodembodiment for forming a signal interconnect includes forming a ZnOemitter in an oxide layer on a semiconductor substrate. The methodincludes confining the ZnO emitter to a circular geometry in the oxidelayer. The oxide layer can be an undoped oxide layer on a siliconsubstrate.

Forming the ZnO emitter includes defining a circular opening in theoxide layer on the silicon. An amorphous buffer layer of ZnO isdeposited next to the silicon. Single crystalline ZnO is then grown onthe buffer layer with p-type doping and then n-type doping. According tovarious embodiments, growing single crystalline ZnO on the buffer layerincludes growing single crystalline ZnO using a hybrid beam deposition(HBD) process. Another embodiment can include growing the singlecrystalline ZnO on the buffer layer using a Metalorganic Chemical VaporDeposition (MO-CVD) process. Another embodiment can include growingsingle crystalline ZnO using an atomic layer deposition (ALD) process.

One embodiment for an optical signal interconnect system includes a ZnOemitter in formed in an oxide layer on a first semiconductor substrateand confined within a circular geometry in the oxide layer. A silicondetector is formed on a second semiconductor substrate which ispositioned to face the silicon detector opposite the ZnO emitter acrossan air gap.

In another embodiment, an optical signal interconnect system includes anoptical waveguide formed in an oxide layer on a silicon substrate. A ZnOemitter is confined within a circular geometry in the oxide layer andcoupled to an input of the optical waveguide. A detector is coupled toan output of the optical waveguide. In some embodiments, the opticalwaveguide is a Zinc Magnesium Oxide (ZnMgO) waveguide and the detectoris a silicon photodiode detector. In some embodiments the opticalwaveguide is a hollow core photonic bandgap waveguide.

In various embodiments the ZnO emitter emits wavelengths ofapproximately 380 nm at a photon energy of approximately 3.3 eV. Inthese embodiments, the detector can be a silicon photodiode detectorcapable of receiving optical signals having a wavelength between 500 and375 nanometers (nm).

FIG. 1A illustrates a cross sectional view of an embodiment of a ZnOlight emitting diode (LED) for use in optical interconnects according toembodiments of the present disclosure. That is, the zinc oxide (ZnO)diode is confined within an opening in an undoped silicon dioxide (SiO₂)layer 102. The opening within the SiO₂ layer 102 has a circular geometryand can have a depth suited to a particular design scale for aparticular integrated circuit, e.g. 50 nm. Embodiments, however, are notlimited to this example depth. In the embodiment shown in FIG. 1A, theZnO diode consists of a buffer layer 104 of ZnO, a p-type doped ZnOlayer 108, and an n-type doped ZnO layer 110.

In various embodiments, the buffer layer 104 is an amorphous layer ofZnO. In various embodiments, the buffer layer 104 can have a thicknessof 10 nm. Again, embodiments, however, are not limited to this examplethickness. The buffer layer 104 can be deposited using chemical vapordeposition (CVD) or other techniques. The buffer layer 104 is depositedin the opening in the silicon dioxide. Next, single crystalline ZnO 106is grown using a number of different techniques. The single crystallineZnO 106 can be doped at different layers to form a p-type dopant layer108 and an n-type dopant layer 110. By way of example, and not by way oflimitation, the p-type dopant layer and the n-type dopant layer may eachhave similar or different thickness, e.g., 20 nm. Once again,embodiments are not limited to these example thicknesses.

In the circular confinement geometry of the SiO₂ layer 102, the crystalgrowth seeds from atoms of the amorphous buffer layer 104 of ZnO. Theopening in the silicon oxide serves to provide optical confinement andincrease the light emitting efficiency of the diode because of thedifferences in the indices of refraction in the ZnO diode and the SiO₂substrate 102 and serves to promote single crystalline growth of the ZnOin the opening.

In various embodiments, the doped ZnO layers can be formed byindividually growing the single crystalline ZnO to the appropriate depthand then doping the ZnO with the respective doping material. In suchembodiments, the p-type doped layer 108 would be formed first. If thismethod is used, the second n-type doped layer 110 is formed on top ofthe p-type doped layer 108 in the same manner.

In some embodiments, the entire ZnO column 106 can be deposited and ap-type dopant, e.g., arsenic, can be ion implanted at a sufficientlyhigh energy to dope only the bottom portion of the single crystallineZnO. The doping of the ZnO is controlled by the energy level with whicheach doping material in driven into the ZnO column. The top portion ofthe single crystalline ZnO is then implanted with an n-type dopant, e.g.gallium, with a sufficiently high energy level.

The single crystalline ZnO can be planarized, e.g., using chemicalmechanical polishing (CMP) or other techniques. The diode is then cappedwith a conductor that defines a circular opening for the emission 114 ofa signal from the ZnO diode. FIG. 1B shows the cap 112 formed ofconductive material that defines a circular opening to generate thesignal from the ZnO diode and allow emission of the optical signal fromthe diode.

In various embodiments, the ZnO diode, e.g., emitter, is formed on asemiconductor substrate 101, e.g., silicon. An oxide layer 102, e.g.,SiO₂, is formed on the substrate 101 and an opening is formed in theoxide layer, e.g., using photolithographic techniques. The oxide layercan be formed to a suitable thickness according to the design rules ofthe device. According to various embodiments, photolithographictechniques are used to from a circular opening in the oxide to exposethe substrate, e.g., silicon layer, underneath. The ZnO diode can beformed through irregular zinc oxide grains that are formed through thepost-growth annealing of high-crystal-quality zinc oxide thin filmsobtained from a filtered cathodic vacuum technique. A hybrid beamdeposition (HBD) process can be used to form the ZnO diode 100 in theSiO₂ substrate 102. This process offers a viable approach to growingdoped and undoped ZnO films, alloys, and devices. The HBD process iscomparable to molecular beam epitaxy (MBE); however, it uses a zincoxide plasma source, which is produced by illuminating a polycrystallineZnO target with either a pulsed laser or an electron beam and a highpressure oxygen plasma created by a radio-frequency oxygen generator.

A hybrid beam deposition (HBD) system utilizes a unique combination ofpulsed laser deposition (PLD) technique and equipment that provides aradical oxygen rf-plasma stream to effectively increase the flux densityof available reactive oxygen at a deposition substrate for the effectivesynthesis of metal oxide thin films. The HBD system further integratesmolecular beam epitaxy (MBE) and/or chemical vapor deposition (CVD)techniques and equipment in combination with the PLD equipment andtechnique and the radical oxygen rf-plasma stream to provide elementalsource materials for the synthesis of undoped and/or doped metal oxidethin films as well as synthesis of undoped and/or doped metal-basedoxide alloy thin films.

A hybrid beam deposition system for synthesizing metal oxide films,doped metal oxide films, metal-based oxide alloy films, and dopedmetal-based oxide alloy films under predetermined synthesis conditionsconsists of a deposition chamber used as a containment chamber forsynthesis of the metal oxide films, doped metal oxide films, metal-basedoxide alloy films, and doped metal-based oxide alloy films under thepredetermined synthesis conditions. A target assembly is used to mount ametal oxide target material within the deposition chamber and an rfreactive gas source introduces an rf oxygen plasma stream into thedeposition chamber within a predetermined dynamical pressure range. Ametal oxide plasma generating subsystem then interacts with the metaloxide target material to generate a high-energy directional metal oxideplasma plume within the deposition chamber. A source material subsystemgenerates, as required, one or more directed streams of elemental sourcematerials into the deposition chamber for the synthesis of doped metaloxide films, metal-based oxide alloy films, and doped metal-based oxidealloy films and a substrate assembly positions. A substrate having asynthesis surface within the deposition chamber in such manner that therf oxygen plasma stream, the high-energy directional metal oxide plasmaplume, and the one or more directed streams of elemental sourcematerials optimally are directed in selected combination or sequences atthe synthesis surface of the substrate. This is done for the synthesisof metal oxide films, doped metal oxide films, metal-based oxide alloyfilms, and doped metal-based oxide alloy films on the substrate withinthe deposition chamber under the predetermined synthesis conditions.

In some embodiments, the ZnO diode can also be formed in the SiO₂substrate 102 by metal organic chemical vapor deposition (MO-CVD).Firstly, a large amount of plasma energy is applied to the siliconsubstrate in a process for depositing a ZnO thin film by sputtering.Hydrogen is dissociated by this energy at low temperature as well as athin film buffer layer, in which an amorphous material and fine crystalsare mixed, is formed by easing the difference of lattice intervalsbetween silicon and zinc oxide.

The system for depositing zinc oxide films by MO-CVD comprises a chambercontaining a heated table, the introduction of the reactants into thechamber in gaseous form and a regulated pumping system to provide adynamic gas flow through the chamber. An organozinc compound and oxidantare carried into the chamber in individual streams of an inert carriergas. Mixing of the organozinc vapor and oxidant occurs before contactwith the heated surface of the substrate in the space between the pointof introduction thereof and the heated substrate surface. Reactionbetween the organozinc compound and oxidant results in decomposition ofthe organozinc compound to produce zinc oxide, which is deposited uponthe substrate as a thin film, with CO₂, CO and volatile hydrocarbons aspossible byproducts of the reaction. The zinc oxide film containshydrogen and may contain a group III element where a volatile compoundof a group III element is also introduced into the deposition chamber.Again, hydrogen is dissociated by this energy at low temperature as wellas a thin film buffer layer, in which an amorphous material and finecrystals are mixed, is formed by easing the difference of latticeintervals between silicon and zinc oxide.

In various embodiments, the ZnO diode can also be formed in the SiO₂substrate 102 by atomic layer deposition (ALD). ZnO films are grown byALD using diethylzinc (DEZn) and H₂O as reactant gases. Self-limitinggrowth occurs at substrate temperatures ranging from 105° C. to 165° C.The self-limiting growth is also achieved when the flow rates of DEZnand H₂O were varied caused by the saturation of all the reaction andpurging steps. It was found that the orientation and surface morphologyof the films is strongly dependent on the substrate temperature. Themobility of films is higher than that of films grown by MO-CVD.

The ALD process begins by introducing gaseous precursors on at a time tothe substrate surface, and between the pulses the reactor is purged withan inert gas or evacuated. In the first reaction step the precursor issaturatively chemisorbed at the substrate surface, and during thesubsequent purging the precursor is removed from the reactor. In thesecond step, another precursor is introduced on the substrate and thedesired film growth reaction takes place. After that the reactionbyproducts and the precursor excess are purged out from the reactor.When the precursor chemistry is favorable, i.e. the precursor absorb andreact with each other aggressively, on ALD cycle can be performed inless than one second in the properly designed flow type reactors.

In the embodiment illustrated in FIG. 2, ZnO emitters 202 on asemiconductor surface of a first die or circuit are arranged to face thesilicon detectors 204 on an adjacent die or circuit and communication isthrough a short air path 206. In operation the electrical contactprovides an electrical current to the diode to excite electronssufficiently to cause optical emission. In various embodiments, asufficient current is provided to release photons having an energy ofapproximately 3.3 eV and a wavelength of 380 nm The ZnO emitter 202emits a signal directionally through the air. The signal travels throughthe air over a short distance, which minimizes diffusion, to a silicondetector 204 where the signal can be received.

FIG. 3 illustrates an embodiment that uses an optical waveguide 302,where the ZnO emitter 304 is at the sending end and the silicon detector306 at the other receiving end. The ZnO optical waveguide 302 canreceive a signal from an emitter 304 and transmit this signal throughthe waveguide 302 to a detector 306 that will receive the signal.According to various embodiments, the wavelengths of the signal emitters304 will be less than the bandgap of ZnO where the ZnO material has avery low loss but can still be high enough that silicon detectors willhave strong absorption.

The ZnO emitter 304 coupled to a ZnMgO waveguide 302 embedded in siliconoxide 308 on a silicon substrate 310 with integrated circuits. A silicondiode receiver 306 can be used at the output of the waveguide 302 toreceive the optical signal and convert it back into an electrical signalto drive another part of the integrated circuit. According to variousembodiments, the wavelength of the emission of the ZnO emitter 302 isless than the bandgap of the ZnMgO, but larger than the bandgap of thesilicon, so it will be strongly absorbed by the silicon detector.

In embodiments in which a ZnO based emitter with a bandgap energy of 3.3eV is used, light can be emitted at 380 nm and absorbed by a ZnOwaveguide. In such embodiments, the ZnO can be doped with Mg to form aZnMgO waveguide. This ZnMgO waveguide has a larger bandgap than ZnO andwill not absorb at 380 nm making it a compatible waveguide for use witha ZnO emitter. If the ZnO diode is made in undoped material it will emitat 380 nm so the waveguide should have a larger bandgap and can be ZnMgOwhich will not absorb at 380 nm but rather only at shorter wavelengths,such as 310 nm. In some embodiments, the waveguides can be a hollow corephotonic bandgap waveguide which will have no absorption and can be madein silicon oxide.

Other embodiments that use optical fibers for use with an opticalemitter are illustrated in FIGS. 4A-8. In FIG. 4A the use of opticalfibers 401 is shown, where the ZnO emitter is at one end and the silicondetector is at the other end. Again the fiber must be made of materialwhich does not absorb the ultraviolet light. The core can be ZnO orZnMgO and the cladding silicon oxide, which when used together do notabsorb the light radiation and energy.

Several examples of optical waveguides and fibers shown in FIGS. 4-8 anddescribed in the following paragraphs can be used to transmit the signalfrom the ZnO diode, e.g., the ZnO diode shown in FIG. 1A. In theembodiment shown in FIG. 4A, the optical fiber has a reflective layerthat is formed on the inner surface of optical fiber 401. In oneembodiment, the reflective layer comprises a metallic mirror that isdeposited with a self-limiting deposition process. This produces areflective surface for optical fiber 401 that is substantially uniform.

In another embodiment of the present disclosure, FIG. 4B illustrates anoptical fiber waveguide 401. The embodiment shown in FIG. 4B includes anoptical fiber 401 that consists of a cladding layer 405 that separatesthe core 403 from the semiconductor wafer. In this structure, thesemiconductor wafer acts as the outer sheath for optical fiber 401.Various materials can be used to form core 403 and cladding layer 405.The core 403 comprises a material with a higher index of refraction thanthe material of cladding layer 405 and thus provides normal opticalfiber waveguide characteristics. Specific examples of materials for core403 and cladding 405 are provided below with respect to FIGS. 4B and 5.

In the embodiment illustrated in FIG. 5, optical fiber 501 comprises acladding layer 505 that separates the core 503 from the semiconductorwafer. In this structure, the semiconductor wafer acts as the outersheath for optical fiber 501. Various materials can be used to form core503 and cladding layer 505. The core 503 comprises a material with ahigher index of refraction than the material of cladding layer 505 andthus provides normal optical fiber waveguide characteristics. Also, anopening 507 runs through the length of the core 503. For example, whenthis opening has a diameter of less than approximately 0.59 times thewavelength of the light transmitted over the optical fiber 501 the lightwill still be guided by core 503.

Since the optical fiber is formed in a wafer of semiconductor material,absorption and radiation in the semiconductor wafer can affect theoperation of the optical fiber. For example, if the wavelength of thelight transmitted in optical fiber 401 is greater the absorption edge ofthe semiconductor wafer, e.g., 1.1 microns for silicon, thensemiconductor wafer will not absorb the light transmitted in opticalfiber 401. However, due to the large change in index of refraction atthe interface between cladding layer 405 and the semiconductor wafer,some radiation loss occurs into the semiconductor wafer. This case isdepicted, for example, in FIG. 6.

FIG. 6 is a graph that illustrates the magnitude of the radiation forthe embodiment of the optical fiber shown in FIG. 4. The graph in FIG. 6shows the magnitude of radiation in an optical fiber, such as opticalfiber 401 as shown in FIG. 4, along the diameter of the optical fiber.In the region of core 403, indicated at 604, optical waves are guidedwith no substantial loss along the length of optical fiber 401.Evanescent fields are present in the region of cladding layer 405indicated at 602. These evanescent fields drop off to insignificantlevels as indicated at 606 in the surrounding semiconductor wafer.

FIG. 7 is a graph that illustrates the magnitude of the radiation forthe embodiment of the optical fiber shown in FIG. 5. The graph in FIG. 7shows the magnitude of radiation in an optical fiber, such as opticalfiber 501 shown in FIG. 5, along the diameter of the optical fiber. Inthe region of opening 507, an evanescent field is present as indicatedat 708. In the region of core 503, radiation in the optical fiber isguided along the length of the fiber without significant loss inintensity as indicated at 704. Evanescent fields are present in theregion of cladding layer 505 as indicated at 702. These evanescentfields drop off to insignificant levels as indicated at 706 in thesurrounding semiconductor wafer.

FIG. 8 illustrates an embodiment of an optical system that includes anemitter that sends a signal through a waveguide to a receiver. Theembodiment in FIG. 8 shows waveguide optical system 801 that includes aradiation source 803 operatively coupled to an input end 807 of 3Dphotonic waveguide 880 so that radiation 821 emitted from the radiationsource is transmitted down the waveguide. Radiation 821 has a wavelengthwithin the photonic bandgap of 3D photonic crystal regions 830 and 840that define waveguide 880. In an example embodiment, radiation source803 includes embodiments of the ZnO diode described in connection withFIGS. 1A and 1B. In various embodiments, the source can be a ZnO diodeaccording to the embodiments described herein.

Radiation 821 is confined in 3D over the entire range of possiblepropagation angles due to the omnidirectional reflection by eachcomplete bandgap crystal surface e.g., lower channel wall 832, thechannel sidewalls (not shown), and an upper surface 842 definingwaveguide 880. Because waveguide 880 may contain either air, another gas(e.g., nitrogen) or a vacuum, the waveguide is expected to have atransmission loss comparable to or better than today's low loss fibers(0.3 dB per kilometer) used for long-distance optical communication.Also, bending losses from bends should be remarkably low as compared toconventional waveguides because the reflection mechanism of completebandgap photonic crystals is not sensitive to incident angle. Thisallows for waveguide 880 to have bends of up to 90 degrees, providingmore design latitude in fabricating waveguide-based integrated circuitsoptical systems such as couplers, Y-junctions, add-drop multiplexers,and the like.

In the embodiment of FIG. 8, a photodetector 836 is operatively coupledto an output end 838 of waveguide 880 to receive and detect radiation821 having traveled down the waveguide, and to generate an electricalsignal (i.e., a photocurrent) 840 in response thereto. Connected tophotodetector 836 is an electronic system 842 operable to receive andprocess electrical signal 840.

The ZnO diode described in the above embodiments uses the opening in thesilicon oxide to provide optical confinement and increase the lightemitting efficiency of the diode because of the differences in theindices of refraction in the ZnO diode and the SiO substrate and servesto promote single crystalline growth of the ZnO in the hole.

CONCLUSION

Methods, devices, and systems for zinc oxide diodes for opticalinterconnects have been shown. The zinc oxide diode emits a signal to bereceived by a silicon detector.

In various embodiments, the zinc oxide diode has a ZnO buffer layer witha p-type ZnO As doped layer and a n-type ZnO Ga doped layer on top. Thezinc oxide diode is formed while confined in the circular hole ofsilicon oxide to promote single crystalline growth, provide opticalconfinement, and increase the light emitting efficiency.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of various embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of skill in the art uponreviewing the above description. The scope of the various embodiments ofthe present disclosure includes other applications in which the abovestructures and methods are used. Therefore, the scope of variousembodiments of the present disclosure should be determined withreference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

In the foregoing Detailed Description, various features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thus,the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment.

1. A method for forming a signal interconnect, comprising: forming a ZnOemitter in an oxide layer on a semiconductor substrate; and confiningthe ZnO emitter to a circular geometry in the oxide layer.
 2. The methodof claim 1, wherein the method includes forming the ZnO emitter in anundoped oxide layer on a silicon substrate.
 3. The method of claim 2,wherein forming the ZnO emitter includes: defining a circular opening inthe oxide layer on the silicon; depositing an amorphous buffer layer ofZnO next to the silicon; and growing single crystalline ZnO on thebuffer layer with p-type doping and then n-type doping.
 4. The method ofclaim 3, wherein growing single crystalline ZnO on the buffer layerincludes growing single crystalline ZnO using a hybrid beam deposition(HBD) process.
 5. The method of claim 3, wherein growing singlecrystalline ZnO on the buffer layer includes growing single crystallineZnO using a Metalorganic Chemical Vapor Deposition (MO-CYD) process. 6.The method of claim 3, wherein growing single crystalline ZnO on thebuffer layer includes growing single crystalline ZnO using an atomiclayer deposition (ALD) process.
 7. A method for forming an opticalsignal interconnect system, comprising: forming a light emitting diodein an undoped oxide layer on a silicon substrate, wherein forming thediode includes; forming an circular opening in the undoped oxide layer;depositing an amorphous buffer layer of Zinc Oxide (ZnO) on the siliconsubstrate within the circular opening; growing single crystalline ZnO onthe buffer layer with p-type doping and then n-type doping; andproviding a conductive contact to the n-type doping on the undoped oxidelayer such that the conductive contact defines a circular opening. 8.The method of claim 7, wherein the method includes providing a metalconductive contact, wherein the circular opening to the conductivecontact has a diameter which is less than a diameter of the circularopening in the undoped oxide layer.
 9. The method of claim 7, whereinthe method includes forming a silicon detector on a different substrateand facing the silicon detector opposite the light emitting diode acrossan air gap.
 10. The method of claim 7, wherein the method includescoupling the light emitting diode to an input of an optical waveguide.11. The method of claim 10, wherein the method includes: coupling thelight emitting diode to an input of a Zinc Magnesium Oxide (ZnMgO)waveguide; and coupling an output of the ZnMgO waveguide to a siliconphotodiode detector.
 12. The method of claim 10, wherein the methodincludes coupling the light emitting diode to an input of a hollow corephotonic bandgap waveguide formed in silicon oxide.
 13. The method ofclaim 12, wherein the method includes: coupling the light emitting diodeto a hollow core photonic bandgap waveguide having a ZnO core; andcoupling an output of the hollow core photonic bandgap waveguide to asilicon detector.
 14. An optical signal interconnect system, comprising:a ZnO emitter in formed in an oxide layer on a first semiconductorsubstrate and confined within a circular geometry in the oxide layer;and a silicon detector on a second semiconductor substrate position toface the silicon detector opposite the ZnO emitter across an air gap.15. An optical signal interconnect system, comprising: an opticalwaveguide formed in an oxide layer on a silicon substrate; a ZnO emitterconfined, within a circular geometry in the oxide layer and coupled toan input of the optical waveguide; and a detector coupled to an outputof the optical waveguide.
 16. The interconnect system of claim 15,wherein: the optical waveguide is a Zinc Magnesium Oxide (ZnMgO)waveguide; and the detector is a silicon photodiode detector.
 17. Theinterconnect system of claim 15, wherein the optical waveguide is ahollow core photonic bandgap waveguide.
 18. The interconnect system ofclaim 15, wherein the ZnO emitter includes a singe crystalline ZnOemitter grown in the circular geometry with p-type doping and thenn-type doping over an amorphous buffer layer of ZnO in contact with thesilicon substrate.
 19. The interconnect system of claim 18, wherein thep-type doping includes Arsenic (As) doping and the n-type dopingincludes Gallium (Ga) doping.
 20. The interconnect system of claim 15,wherein the ZnO emitter emits wavelengths of approximately 380 nm at aphoton energy of approximately 3.3 eV.
 21. The interconnect system ofclaim 15, wherein the detector is a silicon photodiode detector capableof receiving optical signals having a wavelength between 500 and 375nanometers (run).
 22. An optical signal interconnect system, comprising:a ZnO emitter confined within a circular geometry in an oxide layer an asilicon substrate; an optical waveguide fanned in the oxide layer andhaving an input coupled to the ZnO emitter; a detector coupled to anoutput of the optical waveguide; and wherein the ZnO emitter emits awavelength having a photon energy which is less than a bandgap energy ofthe optical waveguide but larger than a bandgap energy of the detector.23. The optical signal interconnect system of claim 22, wherein theoptical waveguide is a Magnesium doped Zinc Oxide (MgZnO) waveguide. 24.A method for operating an optical signal interconnect system,comprising: operating a ZnO emitter confined within a circular geometryin an oxide layer on a silicon substrate to emit optical signals; andusing a silicon photodiode receiver to receive optical signals having awavelength between 500 and 375 nanometers (nm).
 25. The method of claim24, wherein the method includes operating the ZnO emitter to emitultraviolet optical signals.
 26. The method of claim 24, wherein themethod includes operating the ZnO emitter to emit optical signals havinga wavelength of approximately 380 nm and a photon energy ofapproximately 3.3 eV.
 27. The method of claim 24, wherein the method ofoperating includes coupling emissions from the ZnO emitter to an inputof a MgZnO waveguide.
 28. The method of claim 24, wherein the method ofoperating includes coupling emissions between the ZnO emitter and thesilicon photodiode detector through an air gap.
 29. The method of claim24, wherein the method of operating includes coupling emissions from theZnO emitter to an input of a hollow core photonic bandgap waveguide. 30.The method of claim 24, wherein the method includes using the siliconphotodiode detector to detect optical signals optical signals andconvert the optical signals to electrical signals.